1. Field of the Invention
The present invention relates to target ranging and moving target indication and more particularly to a target ranger and moving target indicator for systems requiring range information to a high degree of accuracy and detection of slowly moving targets.
2. Description of the Prior Art
An intrusion detection system determines when the periphery of a protected area has been crossed. Protection of some areas, however, require a determination of intruder penetrator distance to within a few feet and the rate of penetration into the penetrated area, which may be between one and five feet per second for a crawling or walking intruder. Pulse doppler radar techniques may be employed for intruder detection. These systems, however, require extremely wide system bandwidths and extremely narrow doppler filter bandwidths to achieve a desired distance resolution and intrusion rate. In addition, pulse doppler systems may be jammed and thus rendered inoperative.
Impulse radar systems, which transmit pulses having pulse widths in the order of two nano-seconds without the aid of a carrier signal are substantially jam proof. Such systems provide highly accurate intruder detectors. It is well known that the bandwidth established by the generation of a two nanosecond pulse is in the order of 500 Mc. If the 300 Mc spectral line is utilized for the doppler measurement an intruder walking at five feet per second would cause a doppler frequency shift of approximately three cycles per second. In a practical system the width of the spectral lines exceed three cycles per second, thus the rate of intrusion of a walking or crawling intruder cannot be measured by such a system.
It is therefore an object of this invention to provide an intrusion detection system capable of determining intrusion rate after an intruder has penetrated the periphery of a protected area.
It is another object of this invention to provide an intrusion detection system capable of determining the position of an intruder within the protected area to an accuracy of less than one feet.